/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.phoenix.expression;

import java.util.List;
import org.apache.phoenix.expression.visitor.ExpressionVisitor;
import org.apache.phoenix.schema.types.PDataType;

/**
 * Divide expression implementation
 * @since 0.1
 */
public abstract class DivideExpression extends ArithmeticExpression {
  private Integer maxLength;
  private Integer scale;

  public DivideExpression() {
  }

  public DivideExpression(List<Expression> children) {
    super(children);
    Expression firstChild = children.get(0);
    maxLength = getPrecision(firstChild);
    scale = getScale(firstChild);
    for (int i = 1; i < children.size(); i++) {
      Expression childExpr = children.get(i);
      maxLength = getPrecision(maxLength, getPrecision(childExpr), scale, getScale(childExpr));
      scale = getScale(maxLength, getPrecision(childExpr), scale, getScale(childExpr));
    }
  }

  @Override
  public final <T> T accept(ExpressionVisitor<T> visitor) {
    List<T> l = acceptChildren(visitor, visitor.visitEnter(this));
    T t = visitor.visitLeave(this, l);
    if (t == null) {
      t = visitor.defaultReturn(this, l);
    }
    return t;
  }

  @Override
  public String getOperatorString() {
    return " / ";
  }

  private static Integer getPrecision(Integer lp, Integer rp, Integer ls, Integer rs) {
    if (ls == null || rs == null) {
      return PDataType.MAX_PRECISION;
    }
    int val = getScale(lp, rp, ls, rs) + lp - ls + rp;
    return Math.min(PDataType.MAX_PRECISION, val);
  }

  private static Integer getScale(Integer lp, Integer rp, Integer ls, Integer rs) {
    // If we are adding a decimal with scale and precision to a decimal
    // with no precision nor scale, the scale system does not apply.
    if (ls == null || rs == null) {
      return null;
    }
    int val = Math.max(PDataType.MAX_PRECISION - lp + ls - rs, 0);
    return Math.min(PDataType.MAX_PRECISION, val);
  }

  @Override
  public Integer getScale() {
    return scale;
  }

  @Override
  public Integer getMaxLength() {
    return maxLength;
  }
}
